Photoactive lanthanide complexes with phosphine oxides, phosphine oxides-sulfides, pyridine N-oxides, and phosphine oxide-pyridine N-oxides, and devices made with such complexes

ABSTRACT

The present invention is generally directed to luminescent lanthanide compounds with phosphine oxide, phosphine oxide-sulfide, pyridine N-oxide, and phosphine oxide-pyridine N-oxide ligands. It also relates to electronic devices in which the active layer includes a lanthanide complex.

RELATED APPLICATIONS

This application is a non-provisional of U.S. Provisional ApplicationNo. 60/303,283 filed Jul. 5, 2001, the content of which is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to photoactive complexes of lanthanide metalswith phosphine oxide, phosphine oxide-sulfides, pyridine N-oxide, orphosphine oxide-pyridine N-oxide ligands. It also relates to electronicdevices in which the active layer includes a photoactive lanthanidecomplex.

2. Description of the Related Art

Photoactive compounds are of interest in a variety of applications,including analytical, bio-analytical and electronic uses. Extensivestudies have been made of compounds of the lanthanide metals because oftheir characteristic sharp emission spectra with very narrowpeak-widths. Analytical uses of luminescent complexes of lanthanidemetals have been disclosed by, for example, Bell et al. in EP 556 005and EP 744 451.

Organic electronic devices such as devices that emit light, such aslight-emitting diodes that make up displays, are present in manydifferent kinds of electronic equipment. In all such devices, aphotoactive layer is sandwiched between two electrical contact layers.At least one of the electrical contact layers is light-transmitting sothat light can pass through the electrical contact layer. Thephotoactive layer emits light through the light-transmitting electricalcontact layer upon application of electricity across the electricalcontact layers.

It is well known to use organic electroluminescent compounds as theactive component in light-emitting diodes. Electronic devices usingluminescent organometallic complexes of lanthanide metals have also beendisclosed. In most devices the lanthanide centers are bound to diimineligands, such as Skotheim et al., U.S. Pat. No. 5,128,587, and Borner etal., U.S. Pat. No. 5,756,224. Heeger et al. have reported devices usingeuropium complexes blended with semiconducting conjugated polymers (Adv.Mater. 1999, 11, 1349). Devices containing lanthanide centers bound tophosphineoxide ligands have been disclosed in, for example,Kathirgamanathan et al. WO98/58037, Wenlian et al. Journal of the SID1998, 6, 133, and Gao et al. AppL Phys. Lett. 1998, 72, 2217.

There is a continuing need for improved photoactive lanthanidecompounds. Futhermore, the synthesis and luminescent properties oflanthanide complexes bound to phosphine oxide, phosphine oxide-sulfide,N-oxide or phosphine oxide-pyridine N-oxide ligands have remainedlargely unexplored.

SUMMARY OF THE INVENTION

The present invention is directed to a photoactive compound comprisingat least one lanthanide metal compound. The lanthanide metal compoundincludes at least one lanthanide metal which is complexed to at leastone ligand selected from monophosphine oxides having Formula I shown inFIG. 1; bisphosphine dioxides having Formula II, shown in FIG. 1, wherein Formula II,x is 2 and y is 1; trisphosphine trioxide having FormulaII, shown in FIG. 1, where in Formula II,x is 1 and y is 2;bis-phosphine oxide-sulfides having Formula III, shown in FIG. 1;pyridine N-oxides having Formula IV, Formula V or Formula VI, shown inFIG. 2; phosphine oxide-pyridine N-oxides having Formula VII, shown inFIG. 3; and combinations thereof, where:

-   -   in each of Formulae I, II and III:        -   Q is the same or different at each occurrence and is            selected from C₆H_(n)F_(5−n), and C_(m)(H+F)_(2m+1),        -   m is an integer from 1 to 12, and        -   n is 0 or an integer from 1 to 5,    -   in Formula I:        -   Z is selected from Q and pyridyl, with the provision that            when Z is Q, there is at least one F substituent on at least            one Q group,    -   in each of Formulae II and III:        -   LG is the same or different at each occurrence and is a            linking group selected from C_(m)(H+F)_(2m), arylene, cyclic            heteroalkylene, heteroarylene, alkyleneheteroarylene,            ferrocenediyl, and o-carboranediyl,    -   in Formula: II:        -   r is the same or different at each occurrence and is 0 or 1,        -   x is 1 or 2, and        -   y is 1 or 2, with the provision that x+y=3,    -   in each of Formulae IV through VII:        -   Y is the same or different at each occurrence and is            selected from —CN, —OR¹, —OH, —C(O)OR¹, —R_(f), aryl, X,            —NO₂, and —SO₂R¹,        -   R¹ is C_(s)H_(2s+1),        -   R_(f) is C_(s)F_(2s+1)        -   X is F, Cl, Br, or I,        -   s is an integer from 1 to 6,    -   in Formula IV:        -   α is 0 or an integer from 1 to 5,    -   in Formulae V through VII:        -   β is 0 or an integer from 1 to 4,    -   in Formula V:        -   δ is 0 or an integer from 1 to 3, and    -   in Formula VII:        -   m is 0 or an integer from 1-12.

In another embodiment, the present invention is directed to an organicelectronic device having at least one photoactive layer comprising theabove lanthanide compound, or combinations of the above lanthanidecompounds.

As used herein, the term “phosphiie oxide ligand” is intended to mean aligand having one or more phosphine oxide groups, hereinafter shown as“P(O)”. The term “bis-phosphine oxide-sulfide ligand” is intended tomean a ligand having one phosphine oxide group and one phosphine sulfidegroup, where the phosphine sulfide group is hereinafter shown as “P(S)”.The term “pyridine N-oxide ligand” is intended to mean a ligand having asubstituted or unsubstituted pyridine N-oxide fragment. The term“phosphine oxide-pyridine N-oxide” is intended to mean a ligand havingone phosphine oxide group and one pyridine N-oxide fragment.

As used herein, the term “compound” is intended to mean an electricallyuncharged substance made up of molecules that further consist of atoms,wherein the atoms cannot be separated by physical means. The term“ligand” is intended to mean a molecule, ion, or atom that is attachedto the coordination sphere of a metallic ion or an atom. The term“complex”, when used as a noun, is intended to mean a compound having atleast one metallic ion and at least one ligand. The term “group” isintended to mean a part of a compound, such as a substituent in anorganic compound or a ligand in a complex. The term “β-dicarbonyl” isintended to mean a neutral compound in which two carbonyl groups arepresent, separated by a CHR group. The term “β-enolate” is intended tomean the anionic form of the β-dicarbonyl in which the H from the CHRgroup between the two keto groups has been abstracted. The term “chargetransport material” is intended to mean material that can receive acharge from an electrode and move it through the thickness of thematerial with relatively high efficiency and low loss. The phrase“adjacent to,” when used to refer to layers in a device, does notnecessarily mean that one layer is immediately next to another layer. Onthe other hand, the phrase “adjacent R groups”, is used to refer to Rgroups that are next to each other in a chemical formula (i.e., R groupsthat are on atoms joined by a bond). The term “photoactive” refers toany material that exhibits electroluminescence and/or photosensitivity.In addition, the IUPAC numbering system is used throughout, where thegroups from the Periodic Table are numbered from left to right as 1-18(CRC Handbook of Chemistry and Physics, 81^(st) Edition, 2000).

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows Formula I and Formula II for phosphine oxide ligands, andFormula III for bis-phosphine oxide-sulfide ligands, useful in theinvention.

FIG. 2 shows Formulae IV through VI for pyridine N-oxide ligands usefulin the invention.

FIG. 3 shows Formula VII for phosphine oxide-pyridine N-oxide ligandsuseful in the invention.

FIG. 4 shows Formula VIII for enolate ligands useful in the invention.

FIG. 5 shows Formula XVII for a phenylpyridine ligand.

FIG. 6 shows Formula XVIII and Formula XIX for cyclometalated iridiumcomplexes.

FIG. 7 is a schematic diagram of a light-emitting device (LED).

FIG. 8 is a schematic diagram of an LED testing apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the lanthanide compounds of the invention, the lanthanide metals arein the +3 oxidation state, and are heptacoordinate or octacoordinate.One or more of the coordination sites are occupied by at least oneligand having one of Formulae I through VII. More than one of theseligands, and more than one type of ligand may be coordinated to themetal. The remaining coordination sites are occupied by additionalligands, such as halides; β-enolates; anions of acids, such as aceticacid, benzoic acid, picolinic acid, and dipicolinic acid; andnitrogen-containing ligands, such as arylamines, bipyridine,terpyridine, phenanthroline and tetramethylenediamine. When thelanthanide compound is applied as a layer by vapor depositiontechniques, the ligands are generally chosen so that the final compoundis neutral in charge. It is preferred that the additional ligands areβ-enolates. More preferred lanthanide compounds are described by one ofFormulae IX through XV below:Ln(β-enolate)₃(monophosphine oxide)₁   (IX-A)Ln(β-enolate)₃(monophosphine oxide)₂   (IX-B)[Ln(β-enolate)₃]₁(bisphosphine dioxide)¹   (X-A)[Ln(β-enolate)₃]₂(bisphosphine dioxide)₁   (X-B)[Ln(β-enolate)₃]₁(trisphosphine trioxide)₁   (XI-A)[Ln(β-enolate)₃]₂(trisphosphine trioxide)₁   (XI-B)[Ln(β-enolate)₃]₃(trisphosphine trioxide)₁   (XI-C)Ln(β-enolate)₃(bisphosphine oxide-sulfide)₁   (XII-A)Ln(β-enolate)₃(bisphosphine oxide-sulfide)₂   (XII-B)Ln₂(β-enolate)₆(pyridine-N-oxide)₃   (XIII)Ln(β-enolate)₃(phosphine oxide-pyridine N-oxide)₁   (XIV)Ln₂(β-enolate)₆(bisphosphine monoxide)₂MX₂   (XV)Where:

-   -   in Formulae (IX-A) and (IX-B):        -   monophosphine oxide has Formula I shown in FIG. 1;    -   in Formulae (X-A) and (X-B):        -   bisphosphine dioxide has Formula II, shown in FIG. 1;        -   where in Formula II, x is 2, y is 1, and r is 1;    -   in Formulae (XI-A), (XI-B) and (XI-C):        -   trisphosphine trioxide has Formula II, shown in FIG. 1;        -   where in Formula II, x is 1, y is 2, and r is 1;    -   in Formulae (XII-A) and (XI-B):        -   bis-phosphine oxide-sulfide has Formula III, shown in FIG.            1;    -   in Formula (XIII):        -   pyridine N-oxide has Formula IV, Formula V or Formula VI,            shown in FIG. 2;    -   in Formula (XIV):        -   phosphine oxide-pyridine N-oxide has Formula VII, shown in            FIG. 3;    -   in Formula XV:        -   bisphosphine monoxide has Formula II, shown in FIG. 1;        -   where in Formula II, x is 2, y is 1, and r is 0;        -   M is a transition metal;        -   X is a monoanionic ligand

When ligands having more than one phosphine oxide have long linkinggroups, it is possible to coordinate more than one lanthanide metal to asingle ligand, resulting in compounds having Formula (X-A), (X-B),(XI-A) of (XI-B) with 2 or 3 Ln(β-enolate)₃ units. In some cases,oligomeric or polymeric structures can be formed with alternatingLn(β-enolate)₃ units and multi(phosphine oxide) ligands.

It is also possible to form complexes having Formula (XV) with a secondmetal. Preferably the metal M is from Groups 9-11 in the Periodic Table;most preferably Pt. X is an anionic ligand, such as Br⁻, Cl⁻, I—, andCN⁻. It is preferred that X is chloride.

The preferred lanthanide metals are Eu, Tb, and Tm. The preferredlanthanide complexes are neutral and non-ionic, and can be sublimedintact.

Phosphine Oxide Liiands

The phosphine oxide ligands can be monophosphine oxides, bis-phosphinedioxides, or tris-phosphine trioxides, and may include additionalphosphine groups, as in Formula II, when r is 0.

The phosphine oxide ligands having Formula I, shown in FIG. 1, have asingle phosphine oxide group and no additional phosphine groups. It ispreferred that in ligands having this formula at least one of the Qgroups has at least one fluorine. More preferably, at least one Q groupis —C₆F₅; and still more preferably, all the Q groups are —C₆F₅.

Examples of suitable monophosphine oxide ligands having Formula Iinclude, but are not limited to those listed in Table (i) below. Theabbreviation for the monophosphine oxide is given in brackets. TABLE (i)trisf(pentafluorophenyl)phosphine oxide [F₅tpO]2-(diphenylphosphinoyl)-pyridine [dpOpy]

The phosphine oxide ligands having Formula II, shown in FIG. 1, have aphosphine oxide group and at least one additional phosphorus-containinggroup, which can be a phosphine or a phosphine oxide. The phosphorusatoms are joined together by a linking group. The linking group can be asimple hydrocarbon chain or cyclic group, optionally substituted withfluorine atoms or including heteroatoms in place of carbons. The linkinggroup can also be a more complex group, such as a ferrocene oro-carborane group. When ferrocene is the linking group, one phosphorusatom is attached to each cyclopentadiene ring. When o-carborane is thelinking group, a phosphorus atom is attached to each of the two carbonatoms.

Examples of suitable monophosphine oxide ligands having Formula IIinclude, but are not limited to those listed in Table (ii) below. Theabbreviation for the monophosphine oxide is given in brackets. TABLE(ii) (diphenyphosphinomethyl)diphenylphosphine oxide [dppmO](2-diphenyphosphinoethyl)diphenylphosphine oxide [dppeO](3-diphenyphosphinopropyl)diphenylphosphine oxide [dpppO](4-diphenyphosphinobutyl)diphenylphosphine oxide [dppbO]bis(diphenylphosphinomethyl)phenylphosphineoxide [bisdppmO]bis(2-diphenylphosphinoethyl)phenylphosphine oxide [bisdppeO]

Examples of suitable bis-phosphine dioxide and tris-phosphine trioxideligands having Formula II include, but are not limited to those listedin Table (iii) below. The abbreviation for the ligand is given inbrackets. TABLE (iii) bis(diphenylphosphino)methane dioxide [dppmO₂]1,2-bis(diphenylphosphino)ethane dioxide [dppeO₂]1,3-bis(diphenylphosphino)propane dioxide [dpppO₂]1,4-bis(diphenylphosphino)butane dioxide [dppbO₂]1,1′-bis(diphenylphosphino)ferrocene dioxide [dppfcO₂]1,2-bis(diphenylphosphoryl)-o-carborane [dppcbO₂],1,2-bis(di(pentafluorophenyl)phosphino)ethane dioxide [(F₅dppeO₂]bis(2-diphenylphosphinoethyl)phenylphosphine trioxide [bisdppeO₃].

The oxides of monodentate phosphines, dioxides of bidentate phosphines(except for dppfcO₂ and dppcbO₂), and trioxides of tridentate phosphinesare generally prepared by the oxidation of the corresponding phosphinewith aqueous hydrogen peroxide in ethanol, as described in: Ellermann,J.; Schirmacher, D. Chem. Ber. 1967, 100, 2220; Siegl, W. O; Lapporte,S. J.; Collman, J. P. Inorg. Chem. 1971, 10, 2158; Lindner, E.; Beer, H.Chem. Ber. 1972, 105, 3261. The hydrogen peroxide oxidation is also usedto prepare dppcbO₂, but in THF at room temperature.

The bis-phosphine monoxides can be synthesized via the selectivePd-catalyzed biphasic anaerobic oxidation of the corresponding bidentatephosphines with 1,2-dibromoethane in the presence of alkali, asdescribed in: Grushin, V. V. J. Am. Chem. Soc. 1999, 121, 5831; U.S.Pat. No. 5,919,984, 1999. This Pd-catalyzed oxidation is also applied tothe preparation of dppfco₂.

The monophosphine oxide diphenyl phosphonimide tris-phenyl phosphorane[OPNP] is known to form complexes of the formula Ln(β-enolate)₃(OPNP)₁.It has been found in the present study, that it is possible to formcomplexes of the formula Ln(β-enolate)₃(OPNP)₂. OPNP can conveniently beprepared by refluxing bis(triphenylphosphine)iminium chloride in aqueousNaOH.

Bis-phosphine oxide-sulfide Ligands

The bisphosphine oxide-sulfide ligands have Formula III, given above.Examples of suitable bisphosphine oxide-sulfide ligands include, but arenot limited to those listed in Table (iv) below. The abbreviation forthe ligand is given in brackets. TABLE (iv)(1-diphenylphosphoryl-1-diphenylthiophosphoryl)methane [dppmOS](1-diphenylphosphoryl-2-diphenylthiophosphoryl)ethane [dppeOS](1-diphenylphosphoryl-3-diphenylthiophosphoryl)propane [dpppOS]

These ligands can be prepared by the reaction of the correspondingbisphosphine mono-oxide with elemental sulfur.

Pyridine N-Oxide Ligands

The pyridine N-oxide ligands have Formula IV, Formula V, or Formula VI,shown in FIG. 2. Examples of suitable pyridine N-oxide ligands include,but are not limited to those listed in Table (v) below. The abbreviationfor the ligand is given in brackets. TABLE (v) Formula IV pyridineN-oxide [pyO]; and 3-cyanopyridine N-oxide [CNpyO] Formula Vunsubstituted isoquinoline N-oxide Formula VI bipyridine bis(N-oxide)[bipyO₂]

The nitrogen oxide ligands are generally prepared by oxidation ofcorresponding pyridines using oxidants such as peroxyacids.

Phosphine oxide-ivridine N-oxide Ligands

The phosphine oxide-pyridine N-oxide ligands have Formula VII shown inFIG. 3. Examples of this type of ligand include but are not limited tothose listed in Table (vi) below: TABLE (vi)2-(diphenylphosphinoyl)-pyridine-1-oxide [dpOpyO]2-[(diphenylphosphinoyl)methyl]-pyridine-1-oxide [dpmOpyO]

These ligands can be available commercially, or can be made by theoxidation of the corresponding phosphine oxide-pyridine compound asdescribed in: Bodrin, G. V.; Matveeva, A. G.; Terekhova, M. I.;Matrosov, E. I.; Petrov, E. S.; Polikarpov, Yu. M.; Kabachnik, M. I.Izv. Akad. Nauk. SSSR, Ser. Khim. 1991, 912 and McCabe, D. J.; Russell,A. A.; Karthikeyan, S.; Paine, R. T.; Ryan, R. R.; Smith, B. Inorg.Chem. 1987, 26, 1230.

β-Enolate Ligands

The term “β-enolate” is a ligand having Formula VIII, shown in FIG. 4,

-   -   wherein R², R³, R⁴ can be alike or different from each other and        are selected from hydrogen, halogen, substituted or        unsubstituted alkyl, aryl, alkylaryl or heterocyclic groups; or        adjacent R groups can be joined to form five- and six-membered        rings, which can be substituted, and may be N—, O—, or        S-containing heterocyclic rings.        Preferred R² and R⁴ groups are selected from H, F,        —C_(t)H_(u)F_(v), —C₆H₅ which may be substituted with alkyl,        aryl, halide, or combinations thereof, —C₄H₃S, and —C₄H₃O, where        t is an integer from 1 to 6, and u and v are integers such that        u+v=2t+1.Pref erred R³ groups are H, —CH₂-aryl, halide, and        C_(t)H_(u)F_(v).

Examples of suitable β-enolate ligands include, but are not limited to,those listed in Table (vii) below. The abbreviation for the β-enolateform is given in brackets. TABLE (vii) 2,4-pentanedionate [acac]1,3-diphenyl-1,3-propanedionate [DI]2,2,6,6-tetramethyl-3,5-heptanedionate [TMH]1-(2-thienyl)4,4,4-trifluoroacetonate [TTFA]7,7-dimethyl-1,1,1,2,2,3,3-heptafluoro-4,6-octanedionate [FOD]1,1,1,5,5,5-hexafluoro-2,4-pentanedionate [F₆acac]1,1,1,3,5,5,5-heptafluoro-2,4-pentanedionate [F₇acac]1-phenyl-3-methyl-4-i-butyryl-5-pyrazolinonate [PMBP]]

The β-dicarbonyl compounds are generally available commercially.1,1,1,3,5,5,5-heptafluoro-2,4-pentanedione, CF₃C(O)CFHC(O)CF₃, can beprepared using a two-step synthesis, based on the reaction ofperfluoropentene-2 with ammonia, followed by a hydrolysis step asdescribed by M. A. Kurykin, L. S. German, I. L. Knunyants Izv. AN USSR.Ser. Khim. 1980, pp.2817-2829. This compound should be stored andreacted under anyhydrous conditions as it is susceptible to hydrolysis.

Lanthanide Complexes

The lanthanide phosphine oxide and bis-phosphine oxide-sulfide complexesof the invention can be made by the addition of the β-dicarbonyl andphosphine oxide or bis-phosphine oxide-sulfide compounds to a simplelanthanide metal salt, such as the chloride, nitrate, or acetate. Onesynthetic method is to dissolve an anhydrous lanthanide acetate, thedesired β-dicarbonyl and the phosphine oxide in dichloromethane. Theproduct can be precipitated by the addition of hexanes. This isparticularly useful for forming complexes with F₇acac. The F₇acaclanthanide complexes are generally quite stable to air and moisture.Another synthetic route that can be used employs the reaction of atris(β-enolate)lanthanide complex with phosphine oxide or bis-phosphineoxide-sulfide ligands in dichloromethane. The product can be isolatedfrom solvents such as hexane or acetone/hexane.

Examples of lanthanide complexes with phosphine monoxides having theFormula (IX) above, are given in Table 1 below. TABLE 1 Compound Lnβ-enolate phosphine oxide 1 or 2 1-a Eu acac dppmO 2 1-b Eu acac dppeO 21-c Eu acac dpppO 2 1-d Eu acac dppbO 2 1-e Eu acac F₅tpO 2 1-f Eu DIdppmO 2 1-g Eu DI dppeO 2 1-h Eu DI dpppO 2 1-i Eu DI dppbO 2 1-j Eu DIF₅tpO 2 1-k Eu TMH dppmO 1 1-l Eu TMH dppeO 1 1-m Eu TMH dpppO 1 1-n EuTMH dppbO 1 1-o Eu TMH F₅tpO 1 1-p Eu TTFA dppmO 2 1-q Eu TTFA dppeO 21-r Eu TTFA dpppO 2 1-s Eu TTFA dppbO 2 1-t Eu TTFA F₅tpO 2 1-u Eu FODdppmO 2 1-v Eu FOD dppeO 2 1-w Eu FOD dpppO 2 1-x Eu FOD dppbO 2 1-y EuFOD F₅tpO 2 1-z Eu F₇acac dppmO 2 1-aa Eu F₇acac dppeO 2 1-ab Eu F₇acacdpppO 2 1-ac Eu F₇acac dppbO 2 1-ad Eu F₇acac F₅tpO 2 1-ae Tb acac dppmO2 1-af Tb acac dppeO 2 1-ag Tb acac dpppO 2 1-ah Tb acac dppbO 2 1-ai Tbacac F₅tpO 2 1-aj Tb TMH dppmO 1 1-ak Tb TMH dppeO 1 1-al Tb TMH dpppO 11-am Tb TMH dppbO 1 1-an Tb TMH F₅tpO 1 1-ao Tb TTFA dppmO 2 1-ap TbTTFA dppeO 2 1-aq Tb TTFA dpppO 2 1-ar Tb TTFA dppbO 2 1-as Tb TTFAF₅tpO 2 1-at Tb F₇acac dppmO 2 1-au Tb F₇acac dppeO 2 1-av Tb F₇acacdpppO 2 1-aw Tb F₇acac dppbO 2 1-ax Tb F₇acac F5tpO 2 1-ay Tm TMH dppmO1 1-az Tm TMH dppeO 1 1-ba Tm TMH dpppO 1 1-bb Tm TMH dppbO 1 1-bc TbPMBP F₅tpO 2 1-bd Eu F₆acac dppmO 2 1-be Eu F₆acac dppeO 2

Examples of lanthanide complexes with bisphosphine dioxides havingFormula X above, where there is one Ln(β-enolate)₃ unit per phosphineoxide ligand, are given in Table 2 below. TABLE 2 Compound Ln β-enolatephosphine oxide 2-a Eu acac dppmO₂ 2-b Eu acac dppeO₂ 2-c Eu acac dpppO₂2-d Eu acac dppFeO₂ 2-e Eu acac F₅dppeO₂ 2-f Eu DI dppmO₂ 2-g Eu DIdppeO₂ 2-h Eu DI dpppO₂ 2-i Eu DI dppFeO₂ 2-j Eu DI F₅dppeO₂ 2-k Eu TMHdppmO₂ 2-l Eu TMH dppeO₂ 2-m Eu TMH dpppO₂ 2-n Eu TMH dppfcO₂ 2-o Eu TMHF₅dppeO₂ 2-p Eu TTFA dppmO₂ 2-q Eu TTFA dppeO₂ 2-r Eu TTFA dpppO₂ 2-s EuTTFA dppFeO₂ 2-t Eu TTFA F₅dppeO₂ 2-u Eu FOD dppmO₂ 2-v Eu FOD dppeO₂2-w Eu FOD dpppO₂ 2-x Eu FOD dppFeO₂ 2-y Eu FOD F₅dppeO₂ 2-z Eu F₇acacdppmO₂ 2-aa Eu F₇acac dppeO₂ 2-ab Eu F₇acac dpppO₂ 2-ac Eu F₇acacdppFeO₂ 2-ad Eu F₇acac F₅dppeO₂ 2-ae Tb acac dppmO₂ 2-af Tb acac dppeO₂2-ag Tb acac dpppO₂ 2-ah Tb acac dppFeO₂ 2-ai Tb acac F₅dppeO₂ 2-aj TbTMH dppmO₂ 2-ak Tb TMH dppeO₂ 2-al Tb TMH dpppO₂ 2-am Tb TMH dppFeO₂2-an Tb TMH F₅dppeO₂ 2-ao Tb TTFA dppmO₂ 2-ap Tb TTFA dppeO₂ 2-aq TbTTFA dpppO₂ 2-ar Tb TTFA dppFeO₂ 2-as Tb TTFA F₅dppeO₂ 2-at Tb F₇acacdppmO₂ 2-au Tb F₇acac dppeO₂ 2-av Tb F₇acac dpppO₂ 2-aw Tb F₇acacdppFeO₂ 2-ax Tb F₇acac F₅dppeO₂ 2-ay Tm TMH dppmO₂ 2-az Tm TMH dppeO₂2-ba Tm TMH dpppO₂ 2-bb Tm TMH dppFeO₂ 2-bc Tm TMH F₅dppeO₂ 2-bd Tb PMBPdpppO₂

Complexes of the lanthanide metals with pyridine N-oxides, havingFormula XIII above, can be made in CH₂Cl₂ solvent following a reactionof dry metal acetate with excess of the corresponding β-dicarbonylcompound, followed by addition of the N-oxide compound. Novel complexeswith pyridine N-oxides are isolated in 60-90% yield in analytically pureform and characterized by nuclear magnetic resonance (NMR) spectroscopy.

According to data from single crystal X-ray diffraction, the isolatedcomplexes exist in dimeric form with two metals bound through theoxygens of three pyridine N-oxides. Examples of lanthanide complexeswith pyridine N-oxides are given in Table 3 below. The complex hasFormula XIII, shown above. TABLE 3 N-oxide Compound Ln β-enolate Formulaα δ Y 3-a Eu F₆acac IV 0 — — 3-b Tb F₆acac IV 0 — — 3-c Tm F₆acac IV 0 —— 3-d Eu F₆acac IV 1 — 4-CN 3-e Tb F₆acac IV 1 — 4-CN 3-f Eu FOD IV 0 —— 3-g Eu F₇acac IV 0 — — 3-h Eu F₆acac V 0 0 —Electronic Device

The present invention also relates to an electronic device comprising atleast one photoactive layer positioned between two electrical contactlayers, wherein the at least one photoactive layer of the deviceincludes the lanthanide complex of the invention. As shown in FIG. 7, atypical device 100 has an anode layer 110 and a cathode layer 150 andelectroactive layers 120, 130 and optionally 140 between the anode 110and cathode 150. Adjacent to the anode 110 is a hole injection/transportlayer 120. Adjacent to the cathode 150 is an optional layer 140comprising an electron transport material. Between the holeinjection/transport layer 120 and the cathode (or optional electrontransport layer) is the photoactive layer 130.

Depending upon the application of the device 100, the photoactive layer130 can be a light-emitting layer that is activated by an appliedvoltage (such as in a light-emitting diode or light-emittingelectrochemical cell), a layer of material that responds to radiantenergy and generates a signal with or without an applied bias voltage(such as in a photodetector). Examples of photodetectors includephotoconductive cells, photoresistors, photoswitches, phototransistors,and phototubes, and photovoltaic cells, as these terms are describe inMarkus, John, Electronics and Nucleonics Dictionary, 470 and 476(McGraw-Hill, Inc. 1966).

The lanthanide complexes of the invention are useful in the photoactivelayer 130 of the device. For some lanthanide complexes (such as Tb andEu), the luminescence spectrum is due to f-f transitions within themetal. Thus, while the intensity of emission can be influenced by thenature of the ligands attached to the lanthanide metal, the wavelengthremains relatively constant for all complexes of the same metal. Theeuropium complexes typically have a sharp red emission; the terbiumcomplexes have a sharp green emission. For some lanthanides (such asTm), the luminescence observed is not due to atomic transitions of themetal. Rather, it is due to either the ligands or the metal-ligandinteraction. Under such conditions, the luminescence band can be broadand the wavelength can be sensitive to the ligand used.

While the complexes can be used alone in the light-emitting layer, theiremission generally is not strong. It has been found that emission can begreatly improved by combining the lanthanide complexes with materialswhich facilitate charge transport. The materials can be hole transportmaterials, electron transport materials or other light-emittingmaterials which have good transport properties. If the lanthanidecomplex does not have good hole transport properties, a hole transportmaterial can be co-deposited. Conversely, an electron transport materialcan be co-deposited if the lanthanide complex does not have goodelectron transport properties. Some materials can transport bothelectrons and holes and are more flexible to use.

To achieve a high efficiency LED, the HOMO (highest occupied molecularorbital) of the hole transport material should align with the workfunction of the anode, the LUMO (lowest un-occupied molecular orbital)of the electron transport material should align with the work functionof the cathode. Chemical compatibility and sublimation temp of thematerials are also important considerations in selecting the electronand hole transport materials.

It is preferred to use hole transport materials such asN,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine(TPD) and bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane(MPMP);electron and hole transporting material such as4,4′-N,N′-dicarbazole biphenyl (BCP); or light-emitting materials withgood electron and hole transport properties, such as chelated oxinoidcompounds, such as tris(8-hydroxyquinolato)aluminum (Alq₃), andcyclometalated iridium complexes with 2-phenylpyridines and derivatives.

The iridium complexes have been described in copending application Ser.No. 60/215362. They can be generally described as compound havingFormula XVI below:IrL^(a)L^(b)L^(c) _(x)L′_(y)L″_(z),   (XVI)where:

-   -   x=0 or 1, y=0,1 or 2, and z=0 or 1, with the proviso that:        -   x=0 or y+z=0 and        -   when y=2 then z=0;    -   L′=a bidentate ligand or a monodentate ligand, and is not a        phenylpyridine, phenylpyrimidine, or phenylquinoline; with the        proviso that:        -   when L′ is a monodentate ligand, y+z=2, and        -   when L′ is a bidentate ligand, z=0;    -   L″=a monodentate ligand, and is not a phenylpyridine, and        phenylpyrimidine, or phenylquinoline; and    -   L^(a), L^(b) and L^(c) are alike or different from each other        and each of L_(a), L^(b) and L^(c) has Formula XVII, shown in        FIG. 5    -   wherein:        -   adjacent pairs of R⁵—R⁸ and R⁹—R¹² can be joined to form a            five- or six-membered ring,        -   at least one of R⁵—R¹² is selected from F, —CsF₂s+1,            —OCsF_(2s+1), and —OCF₂Y, where s=1-6 and Y═H, Cl, or Br,            and    -   A=C or N, provided that when A=N, there is no R⁵.

Preferred iridium compounds include those where L^(a)=L^(b)=L^(c), andeither (i) R⁷ is CF₃, R¹¹ is F, and all other R are H; or (ii) R¹⁰ isCF₃ and all other R are H. The iridium complexes above are generallyprepared from the appropriate substituted 2-phenylpyridine,phenylpyrimidine, or phenylquinoline. The substituted 2-phenylpyridines,phenylpyrimidines, and phenylquinolines are prepared, in good toexcellent yield, using the Suzuki coupling of the substituted2-chloropyridine, 2-chloropyrimidine or 2-chloroquinoline witharylboronic acid as described in O. Lohse, P. Thevenin, E. WaldvogelSynlett, 1999, 45-48. The iridium complex can then be prepared byreacting an excess of the 2-phenylpyridine, phenylpyrimidine, orphenylquinoline, without a solvent, with iridium trichloride hydrate and3 equivalents of silver trifluoracetate.

When the lanthanide complex is co-deposited with additional chargetransport material to form the photoactive layer, the lanthanide complexis generally present in an amount of about up to 85% by volume (15% byvolume for the charge transport material) based on the total volume ofthe emitting layer. Under such conditions the charge transport materialis responsible for carrying the electrons and/or holes to thelanthanide. The concentration of the charge transport material has to beabove the percolation threshold of approximately 15 volume %, such thata conducting pathway can be established. When the density of thematerial is close to one, 15 wt % is acceptable as long as thepercolation threshold is reached.

In some cases the lanthanide complexes may be present in more than oneisomeric form, or mixtures of different complexes may be present. Itwill be understood that in the above discussion of devices, the term“the lanthanide compound” is intended to encompass mixtures of compoundsand/or isomers.

The device generally also includes a support (not shown) which can beadjacent to the anode or the cathode. Most frequently, the support isadjacent the anode. The support can be flexible or rigid, organic orinorganic. Generally, glass or flexible organic films are used as asupport. The anode 110 is an electrode that is particularly efficientfor injecting or collecting positive charge carriers. The anode ispreferably made of materials containing a metal, mixed metal, alloy,metal oxide or mixed-metal oxide. Suitable metals include the Group 11metals, the metals in Groups 4, 5, and 6, and the Group 8-10 transitionmetals. If the anode is to be light-transmitting, mixed-metal oxides ofGroups 12, 13 and 14 metals, such as indium-tin-oxide, are generallyused. The anode 110 may also comprise an organic material such aspolyaniline as described in “Flexible light-emitting diodes made fromsoluble conducting polymer,” Nature vol. 357, pp 477-479 (11 Jun. 1992).

The anode layer 110 is usually applied by a physical vapor depositionprocess or spin-cast process. The term “physical vapor deposition”refers to various deposition approaches carried out in vacuo. Thus, forexample, physical vapor deposition includes all forms of sputtering,including ion beam sputtering, as well as all forms of vapor depositionsuch as e-beam evaporation and resistance evaporation. A specific formof physical vapor deposition which is useful is rf magnetron sputtering.

There is generally a hole transport layer 120 adjacent the anode.Examples of hole transport materials for layer 120 have been summarizedfor example, in Kirk-Othmer Encyclopedia of Chemical Technology, FourthEdition, Vol. 18, p. 837-860, 1996, by Y. Wang. Both hole transportingmolecules and polymers can be used. Commonly used hole transportingmolecules, in addition to TPD and MPMP mentioned above, are:1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC),N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine (ETPD),tetrakis-(3-methylphenl)-N,N,N′,N′-2,5-phenylenediamine (PDA),a-phenyl-4-N,N-diphenylaminostyrene (TPS), p-(diethylamino)benzaldehydediphenylhydrazone (DEH), triphenylamine (TPA),1-phenyl-3-[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline(PPR or DEASP), 1,2-trans-bis(9H-carbazol-9-yl)cyclobutane (DCZB),N,N,N′,N′-tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine (TTB),and porphyrinic compounds, such as copper phthalocyanine. Commonly usedhole transporting polymers are polyvinylcarbazole,(phenylmethyl)polysilane, poly(3,4-ethylendioxythiophene) (PEDOT), andpolyaniline. It is also possible to obtain hole transporting polymers bydoping hole transporting molecules such as those mentioned above intopolymers such as polystyrene and polycarbonate.

Optional layer 140 can function both to facilitate electron transport,and also serve as a buffer layer or confinement layer to preventquenching reactions at layer interfaces. Preferably, this layer promoteselectron mobility and reduces quenching reactions. Examples of electrontransport materials for optional layer 140 include metal chelatedoxinoid compounds, such as tris(8-hydroxyquinolato)aluminum (Alq₃);phenanthroline-based compounds, such as2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (DDPA) or4,7-diphenyl-1,10-phenanthroline (DPA), and azole compounds such as2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole (PBD) and3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole (TAZ).

The cathode 150 is an electrode that is particularly efficient forinjecting or collecting electrons or negative charge carriers. Thecathode can be any metal or nonmetal having a lower work fimction thanthe first electrical contact layer (in this case, an anode). Materialsfor the second electrical contact layer can be selected from alkalimetals of Group 1 (e.g., Li, Cs), the Group 2 (alkaline earth) metals,the Group 12 metals, the lanthanides, and the actinides. Materials suchas aluminum, indium, calcium, barium, samarium and magnesium, as well ascombinations, can be used.

It is known to have other layers in organic electronic devices. Forexample, there can be a layer (not shown) between the hole transportlayer 120 and the photoactive layer 130 to facilitate positive chargetransport and/or band-gap matching of the layers, or to function as aprotective layer. Similarly, there can be additional layers (not shown)between the photoactive layer 130 and the cathode layer 150 tofacilitate negative charge transport and/or band-gap matching betweenthe layers, or to function as a protective layer. Layers that are knownin the art can be used. In addition, any of the above-described layerscan be made of two or more layers. Alternatively, some or all ofinorganic anode layer 110, the hole transport layer 120, the photoactivelayer 130, and cathode layer 150, may be surface treated to increasecharge carrier transport efficiency. The choice of materials for each ofthe component layers is preferably determined by balancing the goals ofproviding a device with high device efficiency.

It is understood that each functional layer may be made up of more thanone layer.

The device can be prepared by sequentially vapor depositing theindividual layers on a suitable substrate. Substrates such as glass andpolymeric films can be used. Conventional vapor deposition techniquescan be used, such as thermal evaporation, chemical vapor deposition, andthe like. Alternatively, the organic layers can be coated from solutionsor dispersions in suitable solvents, using any conventional coatingtechnique. In general, the different layers will have the followingrange of thicknesses: anode 110, 500-5000 Å, preferably 1000-2000 Å;hole transport layer 120, 50-2500 Å, preferably 200-2000 Å;light-emitting layer 130, 10-1000 Å, preferably 100-800 Å; optionalelectron transport layer 140, 50-1000 Å, preferably 200-800 Å; cathode150, 200-10,000 Å, preferably 300-5000 Å. The location of theelectron-hole recombination zone in the device, and thus the emissionspectrum of the device, is affected by the relative thickness of eachlayer. For examples, when an emitter, such as Alq₃ is used as theelectron transport layer, the electron-hole recombination zone can be inthe Alq₃ layer. The emission would then be that of Alq₃, and not thedesired sharp lanthanide emission. Thus the thickness of theelectron-transport layer must be chosen so that the electron-holerecombination zone is in the light-emitting layer. The desired ratio oflayer thicknesses will depend on the exact nature of the materials used.

It is understood that the efficiency of the devices of the inventionmade with lanthanide compounds, can be further improved by optimizingthe other layers in the device. For example, more efficient cathodessuch as Ca, Ba or LiF can be used. Shaped substrates and novel holetransport materials that result in a reduction in operating voltage orincrease quantum efficiency are also applicable. Additional layers canalso be added to tailor the energy levels of the various layers andfacilitate electroluminescence.

EXAMPLES

The following examples illustrate certain features and advantages of thepresent invention. They are intended to be illustrative of theinvention, but not limiting. All percentages are by weight, unlessotherwise indicated.

In Examples 5,13, 14, and 16-22, photoluminescence of the lanthanidecomplexes was determined qualitatively by placing the solid samplesunder UV light and observing the color of emission.

Example 1

Synthesis of PMBP: 7.5 g 1-phenyl-3-methyl-pyrazolinone was dissolved bywarming in 45 mL p-dioxane. While stirring rapidly, 6 g calciumhydroxide was added to the refluxing solution and then immediatelythereafter 4.4 mL i-butyrylchloride was also added. After an initialwhite precipitate formed, the solution was stirred and refluxed for 30mins during which time the initial solid dissolved and a second whiteprecipitate formed. The solution was cooled and then poured into 100 mL2 M HCl whereupon it becomes dark red and red crystals form on standingfor 48 hrs at room temperature. A mixture of red and white needle-likecrystals was collected by filtration and washed well with distilledwater. Recrystallization from 50:50 methanol:water (wherein the water ispH=4 with HCl) yields 73% fluffy white crystals of the desired productwere collected washed with water and vacuum dried.

Tb(PMBP)³:, 1.7 g terbium nitrate tris-dimethylsulfoxide was dissolvedinto 20 mL methanol and 2.4 g of the ligand PMBP from above was added in20 mL toluene. The cloudy solution was stirred while 2 mL triethylaminewas added. After 15 mins the solution was evaporated to dryness and theoily solid was first washed well with water and then vacuum dried. Theoily white solid was recrystallized from hot toluene:octane 1:1 as awhite powder. This complex exhibited intense green photoluminescent (365nm ex).

Tb(PMBP)₃(F₅tpO).): 1 g of thetris-(1-phenyl-3-methyl-4-i-butyryl-5-pyrozolone)terbium, Tb(PMBP)₃, wasdissolved in 10 mL methylene chloride and then mixed with 0.7 gperfluorotriphenylphosphine oxide also dissolved in 10 mL methylenechloride. The mixture was stirred for 30 mins then evaporated to drynessand the white residue was recrystallized from toluene.

Example 2

This example is illustrative of a typical synthesis of Ln(β-dienolate)₃(bisphosphine dioxide), where β-dienolate is acac, DI,FOD, TMH.

Eu(FOD)₃(dpppO₂). To a dichloromethane (5 mL) solution of Eu(FOD)₃(0.875 g, 0.844 mmol) was added a dpppO₂ (0.375 g, 0.844 mmol) dissolvedin dichloromethane (10 mL). The resulting mixture was stirred for 48 h.The solvent was allowed to evaporate and the resulting white powder waswashed with hexanes, then dried under vacuum. The powder was isolated in62% yield (0.771 g). ³¹P{1H} NMR (CD₂Cl₂, 202 MHz) δ is −48.9.

Example 3

OPNP. To a solution of NaOH (10 g) in water (30 mL) was addedbis(triphenylphosphine)iminium chloride (3.00 g), and the mixture wasstirred under reflux for 2 hours. After addition of water (50 mL) thethick organic oil was separated from the aqueous phase and wahsed withwater. The oily solid was dissolved in dichloromethane (50 mL), theresulting solution was filtered through silica gel, reduced in volume toca. 10 mL, treated with hexanes (200 mL), and left overnight. Theprecipitate was dissolved in dichloromethane (5 mL), and then treatedfirst with ether (10 mL) and after 30 min with hexanes (100 mL). After1.5 hours white crystals of OPNP were separated, washed with hexanes,and dried under vacuum. The yield of spectroscopically pure OPNP was1.40 g (56%). ³¹p NMR (CH₃OH), δ: 17.8 (d, 1P, J=3.7 Hz), 15.1 (d., IP,J=3.7 Hz).

Eu(FOD)₃(OPNP)₂. To a dichloromethane (5 mL) solution of Eu(FOD)₃ (0.627g, 0.651 mmol) was added a OPNP (0.599 g, 1.255 mmol) dissolved indichloromethane (10 mL). The resulting mixture was stirred for 48 h. Thesolvent was allowed to evaporate and the resulting yellow solid waswashed with hexanes, then dried under vacuum. The solid was isolated in92% yield (1.15 g).

Example 4

This example is illustrative of a typical synthesis of Ln(βdienolate)₃(bisphosphine dioxide), where ,β-dienolate=acac, DI, TMH,FOD.

Eu(FOD)₃(dppeO₂). To a dichloromethane (5 mL) solution of Eu(FOD)₃(0.884 g, 0.852 mmol) was added a dppeO₂ (0.366 g, 0.852 mumol)dissolved in dichloromethane (10 mL). The resulting mixture was stirredfor 48 h. The solvent was allowed to evaporate and the resulting whitepowder was washed with hexanes, then dried under vacuum. The powder wasisolated in 62% yield (0.771 g). ³¹P{1H} NMR (CD₂CL₂, 202 MHz) δ is−49.9.

Example 5

(F₇acac)₃Eu(OPNP)₂. 1,1,1,3,5,5,5-heptafluoro-2,4-pentanedione(F7-acetylacetone) was prepared according to the procedure in M. A.Kurykin, L. S. German, Knunaynts, I. L. Izv. Akad. Nauk SSSR, Ser. Khim.1980, 2827., and O. E. Petrova, M. A. Kurykin, D. V. Gorlov Izv. Akad.Nauk. SSSR, Ser. Khim. 1999, 1710. In a glove-box, the F7-acetylacetone(315 mg) was added to a stirred mixture of dry Eu(OAc)₃ (127 mg), OPNP(374 mg), and dichloromethane (1 mL). After a few minutes all solidsdissolved. Hexane (6 mL) was added the clear yellow solution turnedcloudy. After the solution cleared, additional 15 mL of hexane was addedand the mixture was kept at 0 ° C. for 2 hours. Well-shaped crystalswere separated, recrystallized from dichloromethane-hexanes, and driedunder vacuum. The yield was 510 mg (74%). ¹H NMR (CD₂Cl₂), δ: 6.0 (br.s., Ph), 6.8 (br. m., Ph), 7.1 (m, Ph); 7.7 (m, Ph). ¹⁹F NMR (CD₂Cl₂),δ: −74.5 (d, 7F, J=17.5 Hz), −184.7 (heptet, 1F, J=17.5 Hz). ³¹P NMR(CD₂Cl₂), δ: 15.1 (d, 1P J=8.5 Hz), −128.8 (d, IP, J=8.5 Hz). Anal.Calcd for C₇₅H₅₀EuF₂₁N₂O₈P₄: C, 50.6; H, 2.8; N, 1.6. Found: C, 51.3; H,2.9; N, 1.6. This complex exhibited red photoluminescence.

Example 6

Eu(FOD)₃(F5tPO)₂ To a dichloromethane (5 mL) solution of Eu(FOD)₃ (0.608g, 0.586 mmol) was added a F5tpO (0.642 g, 1.172 mmol) dissolved indichloromethane (10 mL). The resulting mixture was stirred for 48 h. Thesolvent was allowed to evaporate and the resulting white powder waswashed with hexanes, then dried under vacuum. The powder was isolated in78% yield (1.036 g). ³¹P{1H} NMR (CD₂Cl₂, 202 MHz) δ −49.3.

Example 7

Tb₁PMBP)₃(dpppO₂) 0.11 g of thetris-(1-phenyl-3-methyl-4-i-butyryl-5-pyrozolone)terbium, Tb(PMBP)₃, wasdissolved in 5 mL methylene chloride and then mixed with 0.054 gbisdiphenylphosphinopropane dioxide also dissolved in 5 mL methylenechloride. The mixture was stirred for 30 mins then evaporated to drynessand the white residue was recrystallized from toluene.

Example 8

Eu(DI)₃(dppbO)₂. To a dichloromethane (2 mL) solution of Eu(DI)₃ (0.161g, 0.195 mmol) was added a dppbO (0.173 g, 0.391 mmol) dissolved indichloromethane (2 mL). The resulting mixture was stirred for 48 h. Thesolvent was allowed to evaporate and the resulting yellow solid waswashed with hexanes, then dried under vacuum. A yellow powder wasisolated in 87 % yield (0.291 g). ³¹P{¹H} NMR (CD₂Cl₂, 202 MHz) δ−15.32. Anal. Calcd for C₇₁H₆₉EuO₈P₄: C, 71.1; H, 5.26; P, 7.26. Found:C, 69.50; H, 4.47; N, 6.60.

Example 9

This example is illustrative of a typical synthesis ofLn(TMH)₃(monophosphine oxide).

Eu(TMH)₃(dpppO). To a dichloromethane (2 mL) solution of the Eu(TMH)₃was added dpppO (0.092 g, 0.124 mmol) dissolved in dichloromethane (2mL) and then stirred for 48 h. The solvent was allowed to evaporate, andthe resulting white solid was washed with hexanes, then dried undervacuum. A white powder was isolated in 36% yield (0.089 g).

Example 10

This example is illustrative of a typical synthesis of Ln (TTFA)₃(monophosphine oxide)₂.

Eu(TTFA)₃(F₅tpO)₂. To a solution of 1-(2-thenoyl) 4,4,4-trifluoroacetate(0.162 g, 0.729 mmol) in dichloromethane (2 mL), triethylamine would beadded (0.101 mL, 0.729 mmol) followed by Eu(NO₃)₃.xH₂O (0.108 g, 0.242mmol) in methanol (2 mL) and F₅tpO (0.135 g, 0.486 mmol) indichloromethane (2 mL). The reaction would be stirred for 48 h followedby evaporation of solvent. The resulting cream powder would berecrystallised from acetone/hexanes with a yield of 50-60%.

Example 11

This example is illustrative of a typical synthesis ofLn(TTFA)₃(bisphosphine dioxide).

Eu(TTFA)₃(dpppO₂). To a solution of 1-(2-thienyl)4,4,4-trifluoroacetate(0.176 g, 0.792 mmol) in dichloromethane (2 mL), triethylamine was added(0.111 mL, 0.792 mmol) followed by Eu(NO₃)₃.xH₂O (0.118 g, 0.265 mmol)in methanol (2 mL) and dpppO₂ (0.118 g, 0.265 mmol) in dichloromethane(2 mL). The reaction was stirred for 48 h. The solvent was allowed toevaporate and the resulting solid was recrystallized fromCH₂Cl₂/hexanes. A fluffy yellow solid was isolated in 93% yield (0.310g). ³¹P{¹H} NMR (CD₂Cl₂, 202 MHz) δ is −47.77 (s).

Example 12

[Eu(F₇acac)₃(OPPh₃)₂]. In a glove-box, the F7-acetylacetone made as inExample 5 (540 mg) was added to a stirred mixture of dry Eu(OAc)₃ (224mg), Ph₃PO (439 mg), and dichloromethane (3 mL). After a few minutes allsolids dissolved. Hexane (15 mL) was added to the clear yellow solutionand the mixture was left at room temperature overnight. Large yellowcrystals of the title complex were separated, washed with hexane, anddried under vacuum. The yield was 630 mg (67%). ¹H NMR (CD₂Cl₂), δ: 7.9(br.m., Ph). ¹⁹F NMR (CD₂Cl₂), δ: −76.9 (7F), −184.9 (1F). ³¹P NMR(CD₂Cl₂), δ: −91.0 (s). Anal. Calcd for C₅H₃₀EuF₂₁O₈P₂: C, 44.3; H, 2.2.Found: C, 44.2; H, 2.3. The structure of the complex was confirmed bysingle-crystal X-ray diffraction. This complex exhibited redphotoluminescence.

Example 13

[Eu(F₆acac)₃(dppeO)₂]. To a stirring mixture of Eu(OAc)₃ (130 mg), dppeO(330 mg), and dichloromethane (ca. 1 mL) was added1,1,1,5,5,5-hexafluoro-2,4-pentanedione (260 mg). All solids dissolvedafter a few minutes. Hexane (20 mL) was added and the solution was keptat 0 ° C. for 1 hour, then left at room temperature overnight. The whiteneedle-shaped crystals were separated, washed with hexanes, and driedunder vacuum. The yield was 555 mg (88%). ¹H NMR (CD₂Cl₂), δ: 3.2 (br.s.), 4.6 (br. s.), 5.8 (br. s.), 7.5 (br. m, Ph); 8.0 (br. m, Ph). ¹⁹FNMR (CD₂Cl₂), δ: −79.7 (s). ³¹P NMR (CD₂Cl₂), δ: −9.9 (d, 1P, J=47.5Hz), −83.2 (d., 1P, J=47.5 Hz). Anal.alcd for C₆₇H₅₁EuF₁₈O₈P₄: C, 50.2;H, 3.2 Found: C, 50.1; H, 3.2. This complex exhibited redphotoluminescence.

Example 14

[Eu(F₆acac)₃(dppmO₂]. A mixture of Eu(OAc)₃ (200 mg), dppmO (502 mg),hexafluoro-2,4-pentanedione (0.44 g), and dichloromethane (4 mL) wasstirred for 10 min. The solution was filtered to remov a small amount ofinsolubles. The clear filtrate was reduced in volume to ca. 1 mL andtreated with hexanes (2 mL). After 10 min the white crystalline solidwas separated, washed with hexanes, and dried under vacuum. The yieldwas 0.793 g (83%). Anal. Calcd. for C₆₅H₄₇O₈F18EuP₄,: C, 49.6; H, 3.0.Found: C, 49.4; H, 2.8. ¹H NMR (CD₂Cl₂, 20 C): 4.4 (br d, J=15.5 Hz, 4H,CH2), 5.8 (br s, 3H, OCCHCO), 7.3 (br m, 24H, 3,4-C6H5), 8.0 (br m, 16H,2-C6H5). ³¹P NMR (CD₂Cl₂, 20 C): −25.2 (br s, 2P, Ph₂P), −78.2 (br s,2P, Ph₂PO). ¹⁹F NMR (CD₂Cl₂, 20 C): −79.9 (s).

Example 15-21

These examples illustrate the synthesis ofpolyfluoroacetylacetonato-pyridine oxide complexes of Eu and Tb.

Example 15

[(F₆acac)₃Eu]₂(pyO)₃. Inside a glove-box,1,1,1,5,5,5-hexafluoro-2,4-pentanedione (360 mg) was added to a stirredmixture of dry Eu(OAc)₃ (170 mg) and dichloromethane (4 mL). After a fewminutes, all solids dissolved and 150 mg of pyridinium N-oxide wasadded. White precipitate started to form immediately. After 2 h solidwas washed with hexane (15 mL), filtered and dried under vacuum. Thematerial was found to be a binuclear complex of Eu, where two europiumatoms (each coordinated to 3 molecules of hexafluoroacetylacetonatoligands) were bridged through oxygen atoms of 3 molecules of pyridiniumN-oxide. The yield was 550 mg (57%). ¹H NMR (acetone-d₆), δ: 5.88 (br.s.), 6.65 ( br. s), 8.61 (br, s) ratio 1:1:2. ¹⁹F NMR (acetone-d₆), δ:−79.12(s). Anal. Calcd for C₄₅H₂₁EU₂F₃₆N₃O₁₅: C, 29.49; H, 1.14, N, 2.29Found: C, 29.32; H, 1.03, N, 2.22. The structure of the complex wasconfirmed by single-crystal X-ray diffraction. The complex exhibited redphotoluminescence.

Example 16

[(F₆acac)₃Tb]₂(pyO)₃. Inside a glove-box,1,1,1,5,5,5-hexafluoro-2,4-pentanedione (660 mg) was added to a stirredmixture of dry Tb(OAc)₃ (340 mg) and dichloromethane (4 mL). After a fewminutes all solids dissolved and 190 mg of pyridinium N-oxide was added.White precipitate started to form immediately. After 2 h solid waswashed with hexane (15 mL), filtered and dried under vacuum. Thematerial was found to be a binuclear complex of Tb, where two terbiumatoms (each coordinated to 3 molecules of hexafluoroacetylacetonatoligands) were bridged through oxygen atoms of 3 molecules of pyridiniumN-oxide. The yield was 990 mg (54%). ¹H NMR (acetone-d₆), δ: 1.90(br.s.). ¹⁹F NMR (acetone-d₆), δ: −65.63(br. s.), −86.48(s). Anal. Calcd forC₄₅H₂₁Tb₂F₃₆N-₃O₁₅: C, 29.26; H, 1.14, N, 2.27 Found: C, 29.45; H, 1.36,N, 2.36.

The compound exhibited green photoluminescence.

Example 17

[(F₇acac)₃Eu]₂pyO)₃. Inside a glove-box,1,1,1,3,5,5,5-heptafluoro-2,4-pentanedione (720 mg) was added to astirred mixture of dry Eu(OAc)₃ (320 mg) and dichloromethane (4 mL).After a few minutes all solids dissolved and 190 mg of pyridiniumN-oxide was added. White precipitate started to form immediately. After2 h solid was washed with hexane (15 mL), filtered and dried undervacuum. The material was found to be a binuclear complex of Eu, wheretwo europium atoms (each coordinated to 3 molecules ofhexafluoroacetylacetonato ligands) were bridged through oxygen atoms of3 molecules of pyridinium N-oxide. The yield was 990 mg (54%), yellowneedles. ¹H NMR (acetone-d₆), δ: 3.20(br. s.), 6.8 (br s), 10.0 (br s).19F NMR (acetone-d₆), δ: −76.40 (6F, br. s.), −184.23(s). Anal. Calcdfor C₄₅H₁₅Eu₂F₄₂N₃O₁₅ : C, 27.84; H, 0.77, N, 2.17 Found: C, 27.76; H,0.95, N, 2.24. Compound exhibited no photoluminescence.

Example 18

[(F₆acac)₃Eu]₂(CNpyO)₃. Inside a glove-box,1,1,1,5,5,5-hexafluoro-2,4-pentanedione (640 mg) was added to a stirredmixture of dry Eu(OAc)₃ (340 mg) and dichloromethane (4 mL). After a fewminutes all solids dissolved and 150 mg of pyridinium N-oxide was added.White precipitate started to form immediately. After 2 h solid waswashed with hexane (15 mL), filtered and dried under vacuum. Thematerial was found to be a binuclear complex of Eu, where two europiumatoms (each coordinated to 3 molecules of hexafluoroacetylacetonatoligands) were bridged through oxygen atoms of 3 molecules of pyridiniumN-oxide. The yield was 850 mg (45%). ¹H NMR (acetone-d₆), δ: 3.1 (br.s.), 3.6 (br s), 7.60 (br s), 8.60 (br s) in ratio 1:2:2:1. ¹⁹F NMR(acetone-d₆), δ: −81.14(s). Anal. Calcd for C₄₈H₁₈Eu₂F₃₆N₆O₁₅: C, 30.24;H, 0.95, N, 4.41 Found: C, 30.67; H, 1.00, N, 4.77. The complexexhibited red photoluminescence.

Example 19

(Fr₆acac)₃Eu](iso-Quinoline-oxide)₃. Inside a glove-box,1,1,1,5,5,5-hexafluoro-2,3-pentanedione (640 mg) was added to a stirredmixture of dry Eu(OAc)₃ (340 mg) and dichloromethane (5 mL). After a fewminutes all solids dissolved and 210 mg of isoquinoline-N-oxide wasadded. After 2 h hexane (15 mL) was added and next morning crystals werefiltered and dried under vacuum. The material was found to be abinuclear complex of Eu, where two europium atoms (each coordinated to 3molecules of hexafluoroacetylacetonato ligands) were bridged throughoxygen atoms of 3 molecules of isoquinoline-N-oxide. The yield was 1300mg mg (66%). ¹H NMR (acetone-d₆), δ: 3.0 (br. s.), 6.5 (br. s.), 7.2(br. s.), 7.8 (br. s.), 8.0 (br. s.), 10.0 (br. s.), in ratio4:2:2:1:2:2. ¹⁹F NMR (acetone-d₆), δ: −79.44(s). Anal. Calcd forC₅₇H₂₇EU₂F₃₆N₃O₁₅: C, 34.55; N, 2.12. Found: C, 34.44; H, 1.22, N, 2.12.The structure of the complex was confirmed by single-crystal X-raydiffraction. The complex exhibited red photoluminescence.

Example 20

[(FOD)₃Eu]₂(pyO)₃. Inside a glove-box,2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedione (FOD) (890 mg)was added to a stirred mixture of dry Eu(OAc)₃ (330 mg) anddichloromethane (4 mL) followed by 180 mg of pyridinium N-oxide. After 2h 15 ml of hexane was added and reaction mixture was kept inrefrigerator overnight. Next morning solid was washed with hexane (15mL), filtered and dried under vacuum. The yield was 1560 mg (68%). ¹HNMR (acetone-d₆), 0.3 (br s), 7.40 (br s), 8.30 (br s), 10.1 (br s),integrated as 28:2:2:1:2.

¹⁹F NMR (acetone-d₆), δ: −82.57 (3F), −126.50(2F), −129.63 (2F). Anal.Calcd for C₇₅H₇₅Eu₂F₄₂N₃O₁₅: C, 38.17; H, 3.20; N, 1.78. Found: C,37.26;H, 3.00; N, 1.40. The complex exhibited red photoluminescence.

Example 21

[(F₆acac)₃Tb]₂(CNpyO)₃. Inside a glove-box,1,1,1,5,5,5-hexafluoro-2,4-pentanedione (620 mg) was added to a stirredmixture of dry Tb(OAc)₃ (340 mg) and dichloromethane (5 mL). After a fewminutes all solids dissolved and 180 mg of p-CN-pyridinium-N-oxide wasadded. White precipitate started to form immediately. After 6 h solidwas washed with hexane (15 mL), filtered and dried under vacuum. Thematerial was found to be a binuclear complex of Eu, where two terbiumatoms (each coordinated to 3 molecules of hexafluoroacetylacetonatoligands) were bridged through oxygen atoms of 3 molecules ofp-CN-pyridinium N-oxide. The yield was 1200 mg (63%). ¹H NMR(acetone-d₆), δ: 7.0 (br. s.). ¹⁹F NMR (acetone-d₆), δ: −56.99 (br.s),−62.36 (br.s), −65.03(s), integrated as 4.5:1:1. Calcd forC₄₈H₁₈Tb₂F₃₆N₆O₁₅C, 30.02; H, 1.02, N, 4.38. Found: C, 35 28.90; H,1.02, N, 5.16. The complex exhibited green photoluminescence.

Example 22

This example illustrates the preparation of iridium complexes which canbe used as a charge transport material.

(a) Preparation of 2-phenylpyridine Ligands

The general procedure used was described in O. Lohse, P. Thevenin, E.Waldvogel Synlett, 1999, 45-48. In a typical experiment, a mixture of200 ml of degassed water, 20 g of potassium carbonate, 150 ml of1,2-dimethoxyethane, 0.5 g of Pd(PPh₃)₄, 0.05 mol of a substituted2-chloropyridine and 0.05 mol of a substituted phenylboronic acid wasrefluxed (80-90° C.) for 16-30 h. The resulting reaction mixture wasdiluted with 300 ml of water and extracted with CH₂Cl₂ (2×100 ml). Thecombined organic layers were dried over MgSO₄, and the solvent removedby vacuum. The liquid products were purified by fractional vacuumdistillation. The solid materials were recrystallized from hexane. Thetypical purity of isolated materials was >98%. The starting materials,yields, melting and boiling points of two 2-phenylpyridines were:

-   -   a1: 2-(4-fluorophenyl)-5-trifluoromethylpyridine

yield 94%. mp=38-40° C.; b.p. 65-67° C./0.07 mm Hg ¹H NMR = 7.08(2H),7.62(1H), 7.90(3H), 8.80(1H), ¹⁹F NMR = −62.75(3F, s) −111.49(m)

Analysis (calculated): C, 60.39 (59.75);

-   -   H, 3.38 (2.90);    -   N, 5.5 (5.51);

a2: 2-(3-trifluoromethylphenyl)pyridine yield 72%, bp=64-65°C./64-65/0.026 mm Hg; ¹H NMR = 7.20(1H), 7.65(4H), 8.1(1H), 8.20(1H),8.65(1H) ¹⁹F NMR = −63.05(3F, s)(b) Preparation of Iridium Complexes, IrL₃

A mixture of IrCl₃.nH₂O (54% Ir; 508 mg),2-(4-fluorophenyl)-5-trifluoromethylpyridine, compound (al) (2.20 g),AgOCOCF₃ (1.01 g), and water (1 mL) was vigorously stirred under a flowof N₂ as the temperature was slowly (30 min) brought up to 185° C. (oilbath). After 2 hours at 185-190° C. the mixture solidified. The mixturewas cooled down to room temperature. The solids were extracted withdichloromethane until the extracts decolorized. The combineddichloromethane solutions were filtered through a short silica columnand evaporated. After methanol (50 mL) was added to the residue theflask was kept at −10° C. overnight. The yellow precipitate of thetris-cyclometalated complex, compound 23-a having Formula XVIII shown inFIG. 6, was separated, washed with methanol, and dried under vacuum.Yield: 1.07 g (82%). X-Ray quality crystals of the complex were obtainedby slowly cooling its warm solution in 1,2-dichloroethane.

Compound 23-b, having Formula XIX shown in FIG. 6, was prepared usingthe same procedure as above using 2-(3-trifluoromethylphenyl)pyridine.

Example 23

dppcbO₂: To a solution of 1,2-bis(diphenylphosphino)-o-carborane (0.59g) in dichloromethane (15 mL) was added 30% hydrogen peroxide (0.3 mL)and the mixture was vigorously stirred at room temperature. After 1hour, analysis of the organic phase by ³¹P NMR indicated 95% conversion.One more 0.3 mL portion of 30% hydrogen peroxide was added and themixture was stirred for one more hour to reach 100% conversion (³¹PNMR). The organic phase was filtered through cotton wool and evaporated.The white crystalline residue was dried under vacuum to give1,2-o-C₂B₁₀H₁₀(P(O)Ph₂₎₂xH₂O quantitatively (0.65 g). ¹H NMR (CD₂Cl₂):7.0-7.2 ppm (m, 3H, m,p-C₆H₄); 8.2 ppm (m, 2H, o-C₆H ₄). ³¹P NMR(CD₂Cl₂): 22.7 ppm (s).

Complexes of the type Ln(βenolate)₃(dppcbO₂) can be prepared followingthe procedure decribed in Example 2.

Examples 24-25

These examples illustrate the synthesis of bimetallic complexes havingFormula XV.

Example 24

{Eu(TMH)₃dppmO}₂PdCl₂: A CH₂Cl₂ (5 mL) solution of PdCl₂ (dppmO)₂ wasadded to a CH₂Cl₂ (5 mL) of Eu(TMH)₃. The resulting solution was stirredat room temperature overnight. The volatiles were evaporated to yield ayellow crystalline solid. The product can be recrystallized from hotCH₂Cl₂. This compound exhibited red photoluminescence.

Example 25

[(acac-F₆)₃Eu(μ-dppeO)₂PdCl₂]_(n): To a solution of[(acac-F₆)₃Eu(dppeO)₂] (160 mg) in dichloromethane (3 mL) was added asolution of [Pd(PhCN)₂Cl₂] (38 mg) in dichloromethane (2 mL). The brownsolution of the Pd complex turned yellow immediately. After the solventwas removed under vacuum the residual oily solid was re-precipitatedfrom dichloromethane (1 mL) with hexane (15 mL) upon trituration.Further trituration with 4 mL of hexane produced a yellow powder. Theyield was 164 mg (92%). Anal. Calcd for (C₆₇H₅₁Cl₂EuF₁₈O₈P₄Pd_(n): C,45.2; H, 2.9. Found: C, 45.8; H, 3.0. This polymer (oligomer) exhibitedred photoluminescence.

Example 26

This example illustrates the formation of OLEDs using the lanthanidecomplexes of the invention.

Thin film OLED devices including a hole transport layer (HT layer),electroluminescent layer (EL layer) and at least one electron transportlayer (ET layer) were fabricated by the thermal evaporation technique.An Edward Auto 306 evaporator with oil diffusion pump was used. The basevacuum for all of the thin film deposition was in the range of 10⁻⁶torr. The deposition chamber was capable of depositing five differentfilms without the need to break up the vacuum.

An indium tin oxide (ITO) coated glass substrate was used, having an ITOlayer of about 1000-2000 Å. The substrate was first patterned by etchingaway the unwanted ITO area with 1N HCl solution, to form a firstelectrode pattern. Polyimide tape was used as the mask. The patternedITO substrates were then cleaned ultrasonically in aqueous detergentsolution. The substrates were then rinsed with distilled water, followedby isopropanol, and then degreased in toluene vapor for ˜3 hours.Alternatively, patterned ITO from Thin Film Devices, Inc was used. TheseITO's are based on Corning 1737 glass coated with 1400 Å ITO coating,with sheet resistance of 30 ohms/square and 80% light transmission.

The cleaned, patterned ITO substrate was then loaded into the vacuumchamber and the chamber was pumped down to 10−6 torr. The substrate wasthen further cleaned using an oxygen plasma for about 5-10 minutes.After cleaning, multiple layers of thin films were then depositedsequentially onto the substrate by thermal evaporation. Finally,patterned metal electrodes of Al were deposited through a mask. Thethickness of the film was measured during deposition using a quartzcrystal monitor (Sycon STC-200). All film thickness reported in theExamples are nominal, calculated assuming the density of the materialdeposited to be one. The completed OLED device was then taken out of thevacuum chamber and characterized immediately without encapsulation.

A summary of the device layers and thicknesses is given in Table 5. Inall cases the anode was ITO as discussed above, and the cathode was Alhaving a thickness in the range of 700-760 Å. In some of the samples, atwo-component electroluminescent (EL) layer was used which containedboth the lanthanides and charge-transport materials. In that case, amixture of the two components, in the ratio indacated, was used as thestarting material and evaporated as described above. TABLE 5 HT layer ELlayer ET layer Sample Thickness, Å thickness, Å thickness, Å 1 MPMPExample 1 Alq₃ 523 639 416 2 MPMP Example 2 + DPA, 107 + 570 TPD (1:1)Alq₃, 414 423 3 MPMP Example 3 + DPA, 119 + 525 TPD (1:1) Alq₃, 311 4064 MPMP Example 4 + DDPA, 109 + 524 TPD (1:1) Alq₃, 306 414 5 MPMPExample 5 + DDPA 507 TPD (1:1) 407 406 6 MPMP Example 1 + DDPA 518 TPD(1:1) 405 410 7 MPMP Example 6 + DPA, 108 + 553 MPMP (1:1) Alq₃, 307 4518 MPMP Example 7 DPA, 524 412 410Alq₃ = tris(8-hydroxyquinolato) aluminumDPA = 4,7-diphenyl-1,10-phenanthrolineDDPA = 2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolineET = electron transportHT = hole transportMPMP = bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane

The OLED samples were characterized by measuring their (1)current-voltage (I-V) curves, (2) electroluminescence radiance versusvoltage, and (3) electroluminescence spectra versus voltage. Theapparatus used, 200, is shown in FIG. 8. The I-V curves of an OLEDsample, 220, were measured with a Keithley Source-Measurement Unit Model237, 280. The electroluminescence radiance (in the unit of Cd/m²) vs.voltage was measured with a Minolta LS-110 luminescence meter, 210,while the voltage was scanned using the Keithley SMU. Theelectroluminescence spectrum was obtained by collecting light using apair of lenses, 230, through an electronic shutter, 240, dispersedthrough a spectrograph, 250, and then measured with a diode arraydetector, 260. All three measurements were performed at the same timeand controlled by a computer, 270. The efficiency of the device atcertain voltage is determined by dividing the electroluminescenceradiance of the LED by the current density needed to run the device. Theunit is in Cd/A.

The results are given in Table 6 below. TABLE 6 ElectroluminescentProperties of Lanthanide Complexes Peak Peak Approximate Peak Radiance,efficiency, Wavelengths, Sample cd/m² cd/A nm 1 30 0.43 550 2 2 0.11 6173 4.5 0.18 617 4 5 0.08 617 5 5.5 0.015 617 6 7 0.021 550 7 0.5 0.01 6178 6 0.5 550

1. A lanthanide compound comprising one of Formulae XII-A and XII-Bbelow:Ln(β-enolate)₃(bisphosphine oxide-sulfide)₁   (XII-A)Ln(β-enolate)₃(bisphosphine oxide-sulfide)₂   (XII-B)where: in Formulae(XII-A) and (XII-B): bis-phosphine oxide-sulfide has Formula IIIQ₂P(S)-LG-P(O)Q₂   (III) such that: in Formula III: Q is the same ordifferent at each occurrence and is selected from C₆H_(n)F_(5−n), andC_(m)(H+F)_(2m+1), m is an integer from 1 to 12, and n is 0 or aninteger from 1 to 5, LG is the same or different at each occurrence andis a linking group selected from C_(m)(H+F)_(2m), arylene, cyclicheteroalkylene, heteroarylene, alkyleneheteroarylene, ferrocenediyl, ando-carboranediyl,
 2. The compound of claim 1 wherein the Ln is selectedfrom Eu, Tb and Tm. 3-4. (canceled)
 5. The compound of claim 1 where inthe bisphosphine oxide-sulfide is selected from(1-diphenylphosphoryl-1-diphenylthiophosphoryl)methane,(1-diphenylphosphoryl-2-diphenylthiophosphoryl)ethane, and(1-diphenylphosphoryl-3-diphenylthiophosphoryl)propane. 6-8. (canceled)9. The compound of claim 1 wherein the β-enolate is selected from2,4-pentanedionate; 1,3-diphenyl-1,3-propanedionate;2,2,6,6-tetramethyl-3,5-heptanedionate;1-(2-thienyl)4,4,4-trifluoroacetate;7,7-dimethyl-1,1,1,2,2,3,3-heptafluoro-4,6-octanedionate;1,1,1,5,5,5-hexafluoro-2,4-pentanedionate;1,1,1,3,5,5,5-heptafluoro-2,4-pentanedionate; and1-phenyl-3-methyl-4-i-butyryl-5-pyrazolinonate.
 10. An electronic devicecomprising a photoactive layer, wherein the photoactive layer comprisesthe lanthanide compound of claim
 1. 11. The device of claim 10 whereinthe lanthanide compound is present in an amount of up to about 85% byvolume based on the total volume of the emitting layer.
 12. The deviceof claim 10 wherein the photoactive layer further comprises a chargetransport material.
 13. The device of claim 12 wherein the chargetransport material is a hole transport material and is selected fromN,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl[-4,4′-diamine;bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane; andcombinations thereof.
 14. The device of claim 12 wherein the chargetransport material is an electron transporting material and is selectedfrom 4,4′-N,N′-dicarbazole biphenyl; chelated oxinoid compounds ofaluminum; cyclometalated iridium complexes with 2-phenylpyridines; andcombinations thereof.
 15. The device of claim 10, further comprising ahole transport layer selected fromN,N′-diphenyl-N,N′-bis(3-methylphenyl)-[1,1′-biphenyl]-4,4′-diamine;1,1-bis[(di-4-tolylamino)phenyl]cyclohexane;N,N′-bis(4-methylphenyl)-N,N′-bis(4-ethylphenyl)-[1,1′-(3,3′-dimethyl)biphenyl]-4,4′-diamine;tetrakis-(3-methylphenyl)-N,N,N′,N′-2,5-phenylenediamine;α-phenyl-4-N,N-diphenyl aminostyrene; p-(diethylamino)-benzaldehydediphenylhydrazone; triphenylamine;bis[4-(N,N-diethylamino)-2-methylphenyl](4-methylphenyl)methane;1-phenyl-3[p-(diethylamino)styryl]-5-[p-(diethylamino)phenyl]pyrazoline;1,2-trans-bis(9H-carbazol-9-yl)cyclobutane;N,N,N′,N′-tetrakis(4-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine;porphyrinic compounds; and combinations thereof.
 16. The device of claim10, further comprising an electron transport layer selected fromtris(8-hydroxyquinolato)aluminum;2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline;4,7-diphenyl-1,10-phenanthroline;2-(4-biphenylyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole;3-(4-biphenylyl)-4-phenyl-5-(4-t-butylphenyl)-1,2,4-triazole; andcombinations thereof. 17-20. (canceled)